1. Field of the Invention
The invention is directed to composite membranes and their use as flashing around window frames, door frames, structural joints and other highly exposed surfaces of building frames or like structures prior to the application of exterior finishing materials, and their use as intermediate layers in the application of exterior finishing materials to building structures.
2. Discussion of Related Art
Composite membranes are commonly used in the construction industry for protecting and waterproofing the frame structure of building frames and roofs. The exposure of a building frame or roofs to environmental factors such as water and moisture can result in devastating damage to the structure. Therefore, it is important for the composite membrane to bond tightly with the structure so environmental factors, such as water and moisture, are not allowed to contact and ultimately harm the structure. Composite membranes are applied to substrates such as a roof, wood framing, steel framing and plywood sheathing, gypsum sheathing and cement board sheathing before any exterior finishing materials are mounted on the substrates. The membranes are formed of materials such as polyethylene and rubberized bitumen or asphalt. Although they adhere well to substrates, these membranes have slick surfaces that are not compatible with conventional bonding materials such as adhesives and base coats normally used to adhere exterior finishing materials such as weather barriers and insulation, to the substrate. As a result, the exterior finishing materials must be mounted onto the composite membrane with mechanical devices such as screws and nails. Although the mechanical devices may effectively secure the exterior finishing materials to the composite membrane as well as the substrate, the mechanical devices must penetrate and perforate the composite membrane creating potential weak points in the membrane where damaging water and moisture may enter. The lack of tight adhesion between the composite membrane and the exterior finishing materials reduces the stability and wind load capacity of the structure.
In light of the problems with conventional composite membranes commonly used in waterproofing systems, it is an object of the present invention to provide a composite membrane that has a rough surface that will bond with materials such as adhesives and base coats.
It is another object of the present invention to provide a method of adhering exterior finishing materials to highly exposed exterior portions of a building structure by utilizing a composite membrane as an intermediate layer between the structure and exterior finishing materials without the use of mechanical devices such as nails and screws.
It is another object of the invention to provide a composite membrane capable of forming a bond with a tensile strength sufficient to withstand design wind loads required of a specific project which may be in excess of 70 PSF.
In accordance with these objectives, the present invention provides a composite membrane having a rough surface that is compatible with bonding materials. This bond-compatible composite membrane comprises a bituminous material layer and a polyester fabric layer. The bond-compatible composite membrane is utilized in a method of waterproofing wood framing, metal framing, plywood, sheathing gypsum, cement board and other highly exposed exterior portions of a structure by adhering the bituminous material layer to the structure and bonding exterior finishing materials such as weather barrier, insulation, exterior cladding and exterior insulation and finishing systems (EIFS) to the polyester fabric layer. The adhesive strength of the bond formed between the polyester fabric layer and the exterior finishing materials is sufficient to hold the exterior finishing materials on the substrate without mechanical devices that will perforate the composite membrane.